If P ⟹ QP \implies QP⟹Q is a true implication, which of the following must also be true?
Q ⟹ PQ \implies PQ⟹P
¬P ⟹ ¬Q\neg P \implies \neg Q¬P⟹¬Q
¬Q ⟹ ¬P\neg Q \implies \neg P¬Q⟹¬P
P∧QP \land QP∧Q